The present invention relates to an anastomotic device for joining a graft vessel to a target vessel at a connection opening present therein.
Anastomoses can in the general sense be subdivided into three types: so-called xe2x80x9cend-to-side anastomosesxe2x80x9d (abbreviated as ETS anastomoses), so-called xe2x80x9cside-to-side anastomosesxe2x80x9d (abbreviated as STS anastomoses) and so-called xe2x80x9cend-to-end anastomosesxe2x80x9d (abbreviated as ETE anastomoses). The anastomotic device according to the invention can be used with any of these three types of anastomoses. An ETS anastomotic is understood to be an anastomotic where one end of one vessel, the graft vessel, is joined to an opening formed in the wall of another vessel, the target vessel. A sort of T-join is thus produced. An STS anastomotic is understood to be an anastomotic where the two vessels to be joined each have an opening formed in their wall, which openings are joined to one another. A so-called ETE anastomotic is understood to be an anastomotic where t-o vessels are joined to one another by joining two vessel ends to one another. This is, as it were, a continuous join where the vessels are located in the extension of one another, for example straight or obliquely at an angle with respect to one another.
According to the invention, the connection opening can thus be either a side opening made in the wall of the target vessel in the case of an ETS or STS anastomotic or an end opening in the case of an ETE anastomotic. The end opening will then be determined by the cutting plane along which the target vessel has been cut through at its end.
According to the invention, the graft vessel and target vessel in this context are in particular blood vessels, but they can also be other hollow tubular organs, such as the urethra, Fallopian tubes, etc. Within the framework of the present invention, the terms graft vessel and target vessel are used as distinguishing terms which serve to distinguish between a first vessel (the graft vessel) and a second vessel (the target vessel). The terms graft vessel and target vessel are thus in no way intended to restrict the invention. Throughout this entire application the terms target vessel and graft vessel can in many cases be interchanged without going beyond the scope of the invention.
Graft vessels which are used in practice and can also be used according to the invention are, inter alia:
the vena saphena magna, which is usually completely detached as a free graft (transplant), but in peripheral vascular surgery is also left in the anatomical position as a so-called in situ graft and joined to neighbouring leg arteries;
the vena saphena parva, which is usually used for transplant purposes and to this end is completely detached;
veins from the arms, which are usually used for transplant purposes;
the arteria thoracica interna, which is usually detached only caudally and is sometimes used as a free graft;
the arteria radialis from the arm, which is used as a free graft;
the arteria gastro-epiploica dextra, which usually is detached only caudally on the spleen side (transponate) and sometimes is used as a free graft;
arteria epigastrica inferior, which in general is used as a free graft;
vessel prostheses made of plastic;
veins or arteries of animal or human material, which in general are stored in the frozen state.
An anastomotic device according to the invention can, for example, be used when making a by-pass in the case of, for example, a blocked coronary artery of the heart. By-pass operations of this type are carried out on a large scale and to date the graft vessel has been attached to the target vessel entirely by hand. In this case in general an opening is made in the aorta wall, where one end of the graft vessel is attached to the edges of the opening by stitching by hand. This join is termed the proximal anastomotic with the aorta. The other end of the graft vessel is joined by hand to the coronary artery beyond the blockage in a corresponding manner by means of suturing. The latter join is also termed the distal anastomotic with the coronary artery. An experienced surgeon is able to complete one anastomotic by suturing in approximately 10 minutes.
Most by-pass operations are also performed using a heart-lung machine, the heart then being temporarily stopped. Since stopping the heart in this way can not only be harmful for the heart itself (after all, the heart no longer has a blood supply) but also for other organs and bodily functions it is important that the time for which the heart is stopped is as short as possible. According to a recent development attempts are being made to perform an increasing number of operations on the beating heart, that is to say without heart-lung machine and without stopping the heart. The reason for this is that operations on the beating heart should be less harmful to the heart and other organs and are much less expensive. In the case of such by-pass operations on the beating heart, the bloodstream is temporarily interrupted at the location of a coronary artery to be by-passed. Also in the case of such a by-pass operation on the beating heart it is extremely important that the interruption to the bloodstream lasts for as short a time as possible, since otherwise a cardiac infarction can occur at this site. An ancillary problem in the case of by-pass operations on a beating heart is that the heart usually has to be lifted in order to be able to reach coronary arteries at the side and bottom of the heart, which in general is poorly tolerated by the heart and can lead to a fall in blood pressure or stoppage of the heart. An anastomotic which can be completed rapidly would make such an operation much more possible.
In addition to the recent development for performing an increasing number of heart operations, such as by-pass operations, on the beating heart, there is also an increasing number of operations which are performed via a small access route or thoracoscopically, there then being little or no possibility for suturing by hand. The aim of the present invention is to provide an aid with which joining of a graft vessel onto a target vessel can be completed in a reliable and reproducible manner, efficiently and with minimum stress on the patient. Said aim is achieved by the provision of accessories with which the conventional, relatively labour-intensive, lengthy and, as far as the result is concerned, less predictable suturing carried out by the surgeon on the body of the patient can be avoided or at least restricted to a minimum.
WO 96/25886, which discloses an anastomotic device of the type mentioned at the beginning, proposes a large number of diverse accessories for the same purpose. The starting point here is the philosophy that there must be no contact between the blood and foreign materials, the corollary of which is the aim to shield all accessories as far as possible by vascular wall material towards the interior of the vessels. However, the measures taken for this purposexe2x80x94i.e. covering all or as many as possible internal, foreign parts with the aid of the wall of the graft vesselxe2x80x94result in a decrease/constriction in the flow aperture available for blood.
The accessories from WO 96/25886 each also have numerous other disadvantages. In many cases the graft vessel has to be stretched, which is possible to only a limited extent or is not possible or is possible only by constricting the graft vessel in another location. Furthermore, with many accessories the wall of the target vessel is punctured by so-called staples. These staples can be driven through the wall of the target vessel from the outside to the inside or driven through the wall of the graft vessel from the inside to the outside by folding arms outwards. Instruments for bending the staples are needed for driving the staples through the wall, both from the inside to the outside and from the outside to the inside. The requisite forces are exerted during this operation, inter alia on the target vessel. When a staple has to be driven through the wall from the outside to the inside in the case of a calcified diseased vessel there is a risk of the staple pushing the wall of the calcified, diseased vessel ahead of it, as a result of which the staples are not able to engage adequately on the wall of the vessel. In the case, in WO 96/25886, of the staples going from the inside to the outside, they usually penetrate both the wall of the aorta or coronary artery (the target vessel) and the wall of the graft vessel. If manipulation has to be from the inside of the target vessel in order to drive the arms and the staples connected thereto through the wall of the target vessel from the inside to the outside, an instrument has to be introduced into the target vessel either via the target vessel or via the graft vessel to be attached. If the graft vessel has already been joined by its other end to another target vessel, this implies an additional surgical intervention in the sense that the instrument has to be brought to the inside somewhere through the wall of a blood vessel and that, on completion, the opening made in a wall for this purpose has to be closed again. If parts of the accessories according to WO 96/25886 are introduced through the opening in the wall of the aorta or coronary artery, the target vessel, said parts usually have circumferential dimensions larger than those of the opening, which implies that the wall of the aorta or coronary artery must allow stretch, at the location of the opening, for introduction of the parts and that the opening must then reduce in size again. Especially in the case of diseased vessels this will generally be unsuccessful or the wall will tear or the opening will permanently remain too large. Furthermore, in WO 96/25886 all openings and all accessories are essentially round, which will give rise to problems when joining a graft vessel to a coronary artery. In general the diameter of the graft vessel is appreciably larger than that of the coronary artery or the target vessel. In the case of the circular or perfectly round ring shape this difference in diameter will give rise to joining problems and be able to impede the ability of the blood vessel to allow passage. After all, the target vessel has a restricted width which can be stretched to only a limited extent.
U.S. Pat. No. 4,350,160 discloses an aid for joining one end of a graft vessel to one end of a coronary artery. The method followed in this case is laborious. A further disadvantage is that the coronary artery has to be cut through transversely and that this fragile coronary artery then has to be bent around a component of the aid instrument. The graft vessel is also bent round, after which the two parts are stapled to one another.
Furthermore, WO 84/00102 discloses an apparatus for joining vessels to one another end-to-end. In this case as well the coronary artery has to be cut through transversely and then folded over a number of pins, which in practice proves to be difficult if not impossible, certainly in the case of very small vessels, such as coronary arteries.
U.S. Pat. No. 5,234,447 discloses an anastomotic device consisting of a ring with staple arms facing downwards from the bottom edge and further staple arms, flanged at their free ends, upright from the top edge. The graft vessel is inserted by its end to be attached, through the ring from top to bottom. Said free end is folded up towards the outside, after which the bottom staple arm is pushed through the folded-over part in order then to be bent round outwards and upwards, after which the entire anastomotic device with graft vessel is pushed into an opening formed in the wall of the target vessel, after which, finally, the bottom staple arms and top staple arms are pushed in the opposite direction through the tissue of the wall of the target vessel surrounding the openings in the target vessel and remain behind with their free pointed ends in said wall tissue of the target vessel. If the tissue of the target vessel is impaired, an anastomotic device of this type is not as suitable for use because of the puncturing of the wall tissue by the staple arms. A further problem can be that if the tissue of the wall of the target vessel is impaired said tissue could also easily tear away, which renders the join unreliable. Moreover, in this case the introduction/insertion into the target vessel will be difficult since the staples on the bottom edge have a diameter larger than that of the opening in the target vessel.
U.S. Pat. No. 4,366,819 discloses a four-part anastomotic device. Said anastomotic device consists of a round, tubular body through which that end of a graft vessel which is to be joined is inserted in order to be wrapped by its free end around the bottom rim of the tubular body. The wrapped-round section is fixed on the tubular body by means of a ring of triangular cross-section. To this end said ring is provided with point-shaped elements which face radially inwards and engage in the wrapped-round section of the graft vessel. Said prepared whole is inserted through an opening in the wall of a target vessel, after which the ring of triangular cross-section is inserted with its sloping top face in contact with the inside of the wall of the target vessel. An outer flange is pushed over the tubular body on the outside of the target vessel, which outer flange is provided with point-shaped elements which face in the longitudinal direction of the target vessel and are inserted in the wall of the target vessel from the outside. The outer and the inner flange are held clamped on one another by a fourth separate component in the form of a ring which can be fixed on the tubular body by means of interior serrations, which interact with exterior serrations provided on the tubular body, in such a way that the compression of tissue between the inner flange and outer flange is maintained. The disadvantage of this construction is that the inner flange already has its outward-facing shape, required for the flange action, before it is inserted in the target vessel and insertion of the prepared whole in the target vessel is thus made more difficult. After all, the diameter of the whole to be inserted inwards is greater than the diameter of the opening in the target vessel.
U.S. Pat. No. 4,368,736 discloses an anastomotic device with which one end of a connecting tube of non-tissue material is inserted in that end of the graft vessel that is to be joined and the other end is inserted in an opening made in the wall of the target vessel. During this operation the graft vessel and target vessel remain some distance apart. With this arrangement the connecting tube can have a bend so that, on the one hand, the connecting tube can be fitted at right angles to the target vessel and, on the other hand, the graft vessel can run at an angle with respect to the target vessel, at least some distance away from the target vessel.
WO 98/40036 discloses an anastomotic device consisting of essentially three basic components. The first basic component, termed xe2x80x98attachment member 12xe2x80x99, consists of a saddle-shaped inner flange with a branch tube, having a cylindrical passage, fixed thereto at an angle of 45xc2x0 or 90xc2x0. The second basic component is the so-called xe2x80x98clamp member 14xe2x80x99, that forms a saddle-shaped outer flange and has a passage through which the branch tube can be inserted. The third basic component is the so-called xe2x80x98locking member 16xe2x80x99, which is a ring that is slidable over the branch tube. The graft vessel can be slid over the branch tube and clamped on the branch tube by means of the third basic component, the xe2x80x98locking memberxe2x80x99. WO 98/40036 does not specify precisely how the first basic component is placed in the target vessel. The saddle-shaped inner flange has dimensions which do not allow it to be inserted from the outside through the connection openings into the target vessel. The branch tube has the disadvantage that it protrudes into the graft vessel and that blood to be passed through the graft vessel will be in contact with the branch tube on flowing through said section of the branch tube.
An anastomotic device according to the precharacterising clause of claim 1 is disclosed in WO 98/03118. This PCT application relates to an xe2x80x9canastomotic finingxe2x80x9d comprising a tubular body, an inner flange, which is provided at the bottom of the tubular body and can consist of arms with cut-outs between them or can be of folded construction, and a flat locking ring, which can be fitted around the tubular body on the outside and acts as outer flange. The way in which said anastomotic fitting is fitted is described from line 4 line 6 of WO 98/03118. For insertion, the arms of the inner flange are in an extended, axial position, the graft vessel is then inserted through the tubular body and the end of the graft vessel is folded back over the extended arms. The folded-back portion of the graft vessel is held in place by means of a locking sleeve. The end of the tubular body with extended arms and graft vessel folded back around them is inserted through an opening in the target vessel and a balloon located in the end with the extended arms is inflated to bend the arms from the axial, extended position (FIG. 6a in WO 98/03118) outwards (FIG. 6b in WO 98/03118) into a radial position (FIG. 6c in WO 98/03118). To fix the graft vessel on the target vessel the locking ring is slid downwards, pins provided on the locking ring penetrating the wall of the target vessel and the wall of that part of the graft vessel that has been folded back and subsequently folded radially outwards. In accordance with WO 98/03118 the inner flange is thus forcibly bent from the axial insertion position into the radial fixing position by means of a balloon. The use of such a balloon has the disadvantage that the latter not only has to be fed through the graft vessel but also that it has to be introduced somewhere via an access and also has to be removed again. This is awkward and complicated, especially if the graft vessel does not still have another free end, for example when said other end has already been fixed to another vessel.
The aim of the present invention is therefore in particular to provide an improved anastomotic device for joining a graft vessel to a target vessel at an opening present therein.
The abovementioned aim is achieved according to a first aspect of the invention by the provision of an anastomotic device for joining a graft vessel to a target vessel at a connection opening present therein, comprising:
an essentially tubular body having a bottom rim to be directed towards the target vessel;
an outer flange that is fitted or can be fitted on the outside of the tubular body and can be brought into contact, around the connection opening, with the outside of the wall of the target vessel; and
an inner flange, formed on the tubular body, which in a free position projects outwards with respect to the tubular body and, overlapping the outer flange around the connection opening, can come into contact with the inside of the wall of the target vessel and which, during insertion of the inner flange in the target vessel, is in an essentially extended position with respect to the tubular body, the inner flange preferably being reversibly bent against a resilient force from the free position into a pretensioned position in which the projection thereof on the plane spanned by the bottom rim of the tubular body is essentially located on and/or inside said lower rim, such that the latter can be inserted through the connection opening in the target vessel, and is fixed in said pretensioned position in a manner such that the fixing can be released in order to bend the inner flange back in the direction of the free position under the influence of the pretension.
A significant advantage of the anastomotic device according to the invention is, on the one hand, that fixing to the target vessel takes place by clamping the tissue surrounding the connection opening between the inner flange and outer flange. The quality of the wall of the target vessel will thus have hardly any influence on the strength of the join of the anastomotic device with the target vessel. This is in contrast to joins based on staples, such as are known from the prior art. Another significant advantage of the anastomotic device according to the invention is that the inner flange is in an extended, parallel or optionally sloping, inward-facing, position when inserting the anastomotic device through the connection opening in the target vessel. What this amounts to is that the inner flange is thus not in a free position projecting outwards with respect to the tubular body, which means that that part of the anastomotic device which is to be inserted through the connection opening in the target vessel has a peripheral contour that is not larger than the peripheral contour of the opening in the target vessel. Thus, that part of the anastomotic device to be inserted in the target vessel fits in said connection opening. Stretching of the tissue of the target vessel around the connection opening or otherwise relatively complex manipulation in order to achieve insertion of the anastomotic device in the connection opening is therefore not necessary. All or part of the inner flange can be brought from the extended position into the outward-facing free position, in which it effectively forms the inner flange, with the aid of mechanical or other instruments. However, it is preferable if the inner flange is reversibly bent, against a resilient force, from the free position into a pretensioned position, that is to say during insertion of the anastomotic device into the connection opening the inner flange is a pretensioned, extended, or inward-facing, inner flange. The way in which this faces inwards can optionally be facing inwards at right angles, but in general the way in which it faces inwards will rather be, preferably gentle (i.e.  less than 15xc2x0), tapering.
Such an anastomotic device with pretensioned, extended inner flange has the advantage that, when fitting the anastomotic device on the target vessel, the inner flange initially faces forwards essentially in the extension of the tubular body or inwards towards the axis of the tubular body (in particular tapers) and consequently can be easily inserted inwards through the connection opening of the target vessel. After the inner flange has been inserted through the connection opening in the target vessel in this way, the fixed, pretensioned position thereof can be released. The inner flange is then able to bend back again into its free position in which it projects, or at least tends to project, laterally with respect to the tubular body and that side thereof which faced outwards in the extended/fixed position comes into contact with the inside of the wall of the target vessel. Fixing to the target vessel is then produced by clamping the wall section of the target vessel located around the opening between the outer flange and the inner flange. If the inner flange has been made from a permanently resilient material, release of the inner flange from the fixed, pretensioned position (or extended position) can, for example, be achieved by pulling back a ring or sleeve fitted around the inner flange on the outside or by removing a cord or other form of restriction fitted around the inner flange. If necessary, it is possible to improve the contact of the inner flange with the inside of the wall of the target vessel by means of an instrument, for example by placing a balloon in the target vessel at the location of the join and inflating said balloon or by exerting mechanical pressure with the aid of another means in order thus to press the inner flange more firmly against the inside wall of the target vessel.
Yet a further significant advantage of the anastomotic device according to the invention is that the protrusion of tissue of the graft vessel into the lumen of the target vessel can be restricted to a minimum or even completely avoided by this means because virtually no internal parts inside the target vessel have to be covered by the graft vessel and neither the graft vessel nor the bottom rim of the tubular body protrudes into, or at least a significant extent into, the lumen of the target vessel.
A further significant advantage of the anastomotic device according to the invention is that when the anastomotic device has been fitted the clamping force exerted on the tissue around the connection opening in the target vessel can be uniformly distributed.
As already indicated at the beginning, the anastomotic device according to the invention can be used with all three types of anastomoses, that is to say ETS anastomoses, STS anastomoses and ETE anastomoses. In the case of an ETE anastomotic the inner flange will preferably face inwards when in the so-called extended position. In the so-called free position and assembled position it will be held in a position extending forwards or facing somewhat outwards by the outer flange (which in the assembled position is located on the outside around the target vessel). If the outer flange is absent and the inner flange is considered completely separately from the remainder of the anastomotic device, said inner flange can assume a shape which in the free position optionally faces radially outwards. In the assembled position said position facing radially outwards will not be able to arise because of the outer flange. In the case of an ETE anastomotic the outer flange will essentially be able to assume the shape of a tube, optionally a cylindrical tube.
In order to be able to facilitate fitting of the anastomotic device under certain conditions, it is advantageous according to the invention if the outer flange is a component which is separate from the tubular body and/or inner flange, is slidable in the longitudinal direction of the tubular body and/or in the direction of the inner flange and can be locked with respect to the tubular body and/or the inner flange by means of locking means. So as to be able, with this arrangement, in the case of an embodiment of the invention which is intended for joining to a target vessel of the type where the connection opening has been made in the wall (that is to say a so-called ETS or STS anastomotic ), to adjust the clamping force with which the wall section of the target vessel surrounding the opening is clamped between the inner flange and outer flange it is advantageous according to the invention if the distance from the outer flange to the tubular body and/or the outward-projecting inner flange is adjustable. In this way it is possible, for example, to obtain a specific, desired clamping force depending on the thickness of the wall of the target vessel. In this context the adjustability can be continuous or discontinuous. According to an advantageous embodiment of the invention, the locking means comprise a mechanism involving serrations. If required, a mechanism of this type involving serrations can also be used to achieve adjustability of the distance from the outer flange to the tubular body and/or the outward-projecting inner flange. An ETE anastomotic can also be carried out in such a way that on sliding the outer flange in the longitudinal direction of the tubular body a compressive force is applied to the vessel wall and the vessel wall is thus clamped firmly between the outer flange and inner flange.
So as to restrict to a minimum, or even completely to avoid, the use of instruments having a mechanical action on the anastomotic device and/or the target vessel and/or the graft vessel, it is advantageous according to the invention if the inner flange is made from a superelastic metal alloy or a thermally activated or activatable alloy with shape memory, such as a nickel-titanium alloy. As an example of a nickel-titanium alloy, the material known by the trade name Nitinol can be used. Such a superelastic metal alloy or a thermally activated/activatable alloy with shape memory has the property that it can be brought from a free state, against a resilient action, into a deformed state and can be fixed in said deformed state by means of a treatment, in general a cold treatment. When said fixing is then released, for example by heating the material to above a certain temperature, the original resilience, which counteracts bending, will return and restore the inner flange to its original free state.
According to a further advantageous embodiment of the invention, the inner flange has a bending axis which extends tangentially with respect to the bottom rim of the tubular body and is located at the level of the inner periphery of the outer flange. What can be achieved in this way is that the anastomotic device does not protrude, or protrudes only slightly, into the target vessel when it has been fitted on the target vessel. Specifically, the inner flange then already bends in the opening via which it is inserted into the target vessel and can then come into flat contact with the inside of the wail of the target vessel from the inside and can even be pressed somewhat into the vessel wall, which consists of flexible material. Because the anastomotic device does not protrude, or hardly protrudes, into the target vessel, the blood flow through the target vessel will also not be impeded or disturbed by sections protruding into the target vessel.
According to a further particular embodiment, which, in particular, can also be used to obtain a bending axis of the inner flange at the level of the inner periphery of the outer flange, or even above this, the inner flange has a number of arms which are separated from one another by notches, cut-outs or folds and are arranged distributed around the periphery of the tubular body, the notches or cut-outs or folds preferably continuing as far as or beyond the outer flange. If the inner flange is made of arms separated from one another by notches or cut-outs, the inner flange can then be regarded as a discontinuous flange, the arms adjacent to one another in the peripheral direction always being separated from one another by notches or cutouts forming discontinuities. However, the flange can also be constructed as a continuous flange, for example by making this of folded construction, at least in the so-called extended or inward-facing position, in which case the outward-facing backs of the folds can be regarded as arms and the fold troughs located between said fold backs can be considered as folds. When the inner flange moves from its pretensioned position (the extended or inward-facing position) into its free position, the fold troughs will be pulled flat (or at least pulled up to a lesser fold trough depth) in order to make it possible for the inner flange to move into the free position and in doing so also to be able to create an uninterrupted inner flange contact surface.
In order to increase the grip of the inner flange on the inner wall of the target vessel it is advantageous according to the invention if that face of the inner flange which in the free position faces towards the inner wall of the target vessel is provided with roughening or unevenness. Said face of the inner flange can optionally also be provided with projections which can interact with cut-outs or holes made in that face of the outer flange which faces towards the vessel wall. Such projections interacting with cut-outs or holes can improve anchoring.
Especially when, in the case of an ETS anastomotic, the graft vessel to be joined has a diameter which is larger than that of the target vesselxe2x80x94which is generally the case when joining a by-pass vessel to the coronary artery, the so-called distal anastomoticxe2x80x94it is advantageous according to a second aspect of the invention, which essentially is independent of the first aspect, if the bottom rim of the tubular body has an essentially oval or elliptical contour. When fitted on the target vessel, the longitudinal axis of the oval or ellipse will then extend essentially parallel to the longitudinal direction of the target vessel. According to the second aspect of the invention, a bottom rim of the tubular body having an essentially oval or elliptical contour is, however, also advantageous if the graft vessel has to be joined to the target vessel at an angle, as can be the case with an ETS anastomotic irrespective of the relationship between graft vessel and target vessel diameter, and can also be the case with an ETE or STS anastomotic. Such an anastomotic device of oval or elliptical design can also very readily be produced by modifying in this sense anastomotic devices known from the prior art.
According to a third aspect of the invention, which can be used independently of the first and/or second aspect but highly advantageously can also be used in combination with the first and/or second aspect, the invention relates to an anastomotic device for joining a graft vessel to a target vessel at an opening present therein, such as, in particular, an opening present in the wall thereof, comprising an outer flange which is intended to be brought into contact, by means of an outer flange contact surface, with the outside of the wall of the target vessel around the opening, characterised in that the outer flange contact surface is of cylindrically curved construction, preferably with a radius of curvature which is equal to or approximately equal to the external circumferential radius of the target vessel at the location of the opening. By making the outer flange contact surface of cylindrically curved construction, constriction of the target vessel at the location of and as a consequence of the anastomotic device is reduced or, if the radius of curvature is equal to or approximately equal to the external radius of the target vessel at the location of the opening, even completely prevented. Reduction of the constriction or complete preclusion of the constriction of the target vessel at the location of the anastomotic device has the advantage that the flow through the target vessel at the location of the anastomotic device is impeded to a lesser extent or is even not impeded at all. Such a cylindrically curved outer flange can, in particular, be advantageously used in the case of an STS or ETS anastomotic. It will be clear that a cylindrically shaped outer flange of this type can also very readily be achieved by modifying in this sense anastomotic devices known from the prior art.
In order further to counteract compression of the target vessel and, consequently, thus constriction of the target vessel at the location of the anastomotic device, it is particularly advantageous, in the case of said third aspect according to the invention, if the outer flange contact surface has the shape of, essentially, a cylinder sector which extends over at most 180xc2x0. Extension of the cylinder sector over more than 180xc2x0 is not entirely precluded, but this makes fitting the anastomotic device on the target vessel, and fixing it thereto, somewhat more complicated since in this case either the target vessel has to be pinched together to some extent in order to be able to place this in the cylinder sector section of the outer flange or the cylinder sector section must be constructed such that it is either flexible or can be bent open. The cylinder sector will preferably extend over a range of 150xc2x0 to 180xc2x0. What can be achieved by the use of such a cylinder sector section for the outer flange contact surface is that the outer flange is able to bear on tissue that is located around the target vessel, in particular tissue in which the target vessel is embedded. The tissue located on/over the target vessel and, if necessary, the tissue alongside the target vessel is removed or pushed aside to a small extent, after which the outer flange is then able to sink into the tissue and is able to bear thereon. It should be clear that constriction of the target vessel is reliably extensively prevented/avoided by this means.
For applications in coronary artery surgery the radius of curvature of the outer flange contact surface will, according to an advantageous embodiment of the invention, be in the range from 0.5 to 1.25 mm for distal anastomotic at the location of the coronary artery, (which here in general has a diameter of 1 to 2.5 mm). In the case of a proximal anastomotic at the aorta ascendens, which then in general has a diameter of 3 to 5 cm at this location, the radius of curvature of the outer flange contact surface will be in the range from 15 to 25 mm.
In order to achieve a uniform clamping force around the opening in the target vessel with an anastomotic device having a curved outer flange contact surface, it is advantageous according to the invention if, when using an inner flange having an interrupted or uninterrupted inner flange contact surface, the inner flange is of cylindrically curved construction with a radius of curvature which
is equal to or approximately equal to the internal circumferential radius of the target vessel at the location of the opening; or
is equal to or approximately equal to the radius of curvature of the outer flange contact surface.
For coronary artery surgery the radius of curvature of the inner flange contact surface will then, corresponding to the radius of curvature of the outer flange contact surface, preferably be in the range from 0.5 to 1.25 mm in the case of distal anastomotic with the coronary artery or in the range from 15 to 25 mm in the case of proximal anastomotic with the aorta.
In the case of proximal aorta anastomotic, the aorta ascendens displays (slight) curvature towards the left-hand side of the patient (towards the right-hand side from the surgeon""s view) at the location of the anastomotic. In order to improve the join even further it can thus be advantageous if the outer flange contact surface, and optionally also the inner flange, is constructed not only with the abovementioned cylindrical shape (in the anteroposterior direction of the patient, the so-called sagittal plane) in the longitudinal direction of the aorta (or outer flange), but also concave in the case of the outer flange or convex in the case of the inner flange.
In order fully to complete the join between the target vessel and the graft vessel it is advantageous according to the invention if the anastomotic device further comprises coupling means for fixing the free end of the graft vessel (or target vessel) to the anastomotic device, for example the tubular body thereof, or for fixing a first anastomotic device to a second anastomotic device. With this arrangement, fixing of the graft vessel (target vessel) could take place directly at, for example, the outer flange or at a component that has been made in one piece with the tubular body and/or the outer flange. Such a component made in one piece with the tubular body can optionally be located inside the tubular body. However, fixing can also take place to a separate, independent component which, after the graft vessel has been fixed thereto, is coupled to the anastomotic device.
According to a farther advantageous embodiment of the invention, with this arrangement the coupling means comprise an accessory which has a passage for the graft vessel and can be at least partially inserted in the tubular body, the tubular body and/or the accessory preferably being provided with a stop which is arranged such that it prevents the accessory from being able to protrude beyond the bottom rim of the tubular body. If the coupling means comprise a separate accessory which can be inserted in the tubular body, fixing of the graft vessel to the anastomotic device outside the body is relatively simplified, the anastomotic device itself can be of relatively simpler construction and fixing of the anastomotic device to the target vessel can be achieved relatively easily since, if appropriate, it is easy here to use an instrument that can be placed through the anastomotic device into the target vessel and can then be removed so as, finally, actually to produce the join of the graft vessel on the target vessel by means of said accessory.
The coupling means can thus comprise a separate component that is fixed to the anastomotic device, for example to the tubular body, for example after the tubular body has first been fixed by means of inner flange and outer flange to the target vessel, but the coupling means can also have been formed in one piece with the anastomotic device, for example with the tubular body, in which case in general the graft vessel will first be joined to the tubular body and only then will the tubular body be fixed to the target vessel by means of the inner flange and outer flange. In this latter case joining of the tubular body to the graft vessel can take place outside the patient""s body and in the former case joining of the graft vessel to the separate auxiliary coupling piece can take place outside the patient""s body.
In order to be able to join the graft vessel without constricting this, or possibly with minimal constriction, by means of the anastomotic device, it is advantageous if the coupling means have a series of passages for suture which are arranged around the periphery of the tubular body or the separate accessory and pass through the tubular body or the separate auxiliary coupling piece, the passages preferably having a diameter of approximately 0.5 to 1.5 mm. Said passages will run essentially radially with respect to the graft vessel or the tubular body or the auxiliary coupling piece.
According to an advantageous embodiment of the invention, the coupling means comprise a flexible and/or resilient ring which is sized such that the connection end of the graft vessel can be inserted through it and wrapped back over it, a peripheral groove, which opens inwards and in which the ring, together with part of the folded-back connection end of the graft vessel, can be accommodated, preferably in a tight-fitting manner, being provided in an internal peripheral surface of the anastomotic device, preferably of the tubular body thereof. Such a flexible and/or resilient ring in combination with a peripheral groove makes it possible for the anastomotic device to be fixed to the target vessel first and for the graft vessel, after it has been provided with the flexible and/or resilient ring, then to be joined to the anastomotic device by deforming the flexible and/or resilient ring and inserting this in the anastomotic device and accommodating it in the peripheral groove, preferably in a tight-fitting manner. With this arrangement pulling free of the graft vessel can advantageously be counteracted by allowing the peripheral groove to open at a dowmward slope into the target vessel. According to an advantageous embodiment, manipulation of the flexible and/or resilient ring is facilitated if two or more rod-shaped parts are fixed to the ring, which rod-shaped parts are essentially at right angles to the ring, extend in the axial direction thereof and are fixed at the other ends to a flexible sleeve. By pinching or otherwise deforming the flexible sleeve, the ring can then be deformed via the rod-shaped parts and manipulated in order to be able to insert it in the anastomotic device and fit it in the peripheral groove.
According to a farther advantageous embodiment of the invention, the coupling means can comprise an outwardly tapering tube, which is sized such that the connection end of the graft vessel can be inserted through it and folded back over it, and a clamping ring which can be slid over the tube from the narrow end, with the folded-back part of the graft vessel lying between the ring and the tube, until the ring is firmly clamped on the tube, with the folded-back part of the graft vessel lying between ring and tube. Coupling means of this type can be produced very simply and are also easy to use. With this arrangement, the clamping ring and/or the outwardly tapering tube can have been provided with locking means in order to be able to lock these to the remainder of the anastomotic device to produce the join of the graft vessel on the target vessel.
The coupling means as described in particular in claims 15-23 can optionally also be used entirely independently of aspects 1 to 4 according to the invention.
If, in the case of the coupling means, a distinction is made between, on the one hand, coupling means with which separate, additional coupling accessories are not needed and, on the other hand, coupling means with which separate, additional coupling accessories are needed, the following can then be pointed out. Coupling means with which additional coupling accessories are not needed can, for example, comprise a ring of holes running all round the anastomotic device, which can advantageously be used in ETS and ETE anastomoses in particular. Such a ring of holes can be made in an upright ring-like or cylindrical part, which is placed on the outside of the outer flange, and can be regarded as the tubular body. In the case of coupling means without additional accessories consideration can also be given to coupling means for coupling two anastomotic devices to one another, for example by providing one with an internal groove in which an external rib of the other fits, as can be useful in the case of STS anastomoses and also ETS and ETE anastomoses. As will be seen from the description of the figures, diverse embodiments are conceivable here. In the case of coupling means with which one or more separate, additional coupling accessories are needed, consideration can be given, in a simple form, for example, to a straight tube through which the graft vessel is inserted and is folded back around it by its end, after which a ligature or tie wrap is applied from the outside, after which the whole can then be fitted in the tubular body and fixed, for example by clamping or any form of coupling, such as a mechanism involving serrations, or barbs. However, other possibilities are also not only conceivable but also realistic. For example, consideration can be given to the use of a flexible ring around the end of the graft vessel, which ring, in turn, can be accommodated in a groove or slit made in the anastomotic device, or to a tube through which a graft vessel is inserted and wrapped round at one end so as to be clamped on the tube by means of a slidable ring, which whole can then be fitted and fixed in the anastomotic device.
In order further to improve the join of the graft vessel to the target vessel, in particular in the case of an ETS anastomotic when the target vessel is the coronary artery, it is advantageous according to a fourth aspect of the invention if the passage through the tubular body and/or the passage through the accessory which can be inserted through the latter and/or the coupling means are equipped such that the graft vessel is joined at an angle which is not equal to 90xc2x0 and is preferably less than 70xc2x0, such as, for example, 60xc2x0, 45xc2x0 or 30xc2x0, with respect to the target vessel. What this will amount to in the case of the passage through the tubular body being suitably equipped and/or the passage through the accessory which is insertable in the tubular body being suitably equipped is that the respective passage is positioned at an angle with respect to the outer flange. In use, the respective passage will then accommodate the end of the graft vessel to be joined or be located in the extension thereof. Said fourth aspect can be used either independently of the first and/or second and/or third aspect of the invention, for example with the prior art such as, for example, WO 96/25886, or in combination with the first and/or second and/or third aspect according to this invention. The advantage of an oblique join of the graft vessel on the target vessel is that in the case of a heart by-pass the effect of the pericardium or other structures, such as the lungs, in the vicinity thereof on the graft vessel is reduced. Specifically, in the case of an (approximately) right angle join such an effect can easily lead to bending or kinking of the graft vessel or compression of the graft vessel or target vessel and thus impede the blood flow.
In the case of an oblique join of the graft vessel to the target vessel, the anastomotic device, or at least one or more parts thereof located transversely on the target vessel, will have an essentially oval or elliptical shape/contour. In the case of the join of a graft vessel to a coronary artery said oval or elliptical shape/contour will be much more pronounced than in the case of the join of a graft vessel to the aorta.
In order to counteract rejection phenomena it is advantageous according to the invention if the anastomotic device according to the invention is made of or coated with a material that is inert with respect to the human or animal body, such as types of high grade stainless steel, titanium and Teflon-like plastics or other plastics, which may or may not be based on Teflon.
In order to counteract clotting phenomena it is advantageous according to the invention if the anastomotic device according to the invention, or at least the inner flange and/or arms of the anastomotic device and/or those parts of the anastomotic device which come into contact with blood are coated with materials which counteract blood clotting. Materials of this type which prevent or counteract blood clotting are known per se. In this context consideration can be given to a carbon coating, a heparin coating or a so-called negative charge. An example of a material which inhibits blood clotting is silicon carbon.
However, it is not precluded that in practice the invention is used in combination with the use of rejection inhibitors and/or anticoagulants (thrombosis inhibitors) by the patient.